This invention concerns a magnetic bubble memory device, and more particularly it concerns an improvement of its operating characteristics wherein the intensity of a rotating field applied during the memory operation is radically decreased.
Generally in the magnetic bubble memory device, the following three major advantages are achieved by minimizing the intensity of the rotating field applied parallel to the major surface of the magnetic bubble memory chip:
(1) The power consumption in the magnetic bubble memory device is attributable to the rotating field and the power consumed by the rotating field increases in 2nd power of proportion to the intensity of the rotating field. Accordingly, with a smaller intensity of the rotating field, the power consumption can be saved greatly;
(2) The temperature rise in the magnetic bubble memory chip can be minimized and the operating temperature range of the magnetic bubble memory device can be extended accordingly. This is because the chip temperature is raised by heat originating from the power consumption in the rotating field. Accordingly, the temperature rise increases in proportion to the power consumption. A smaller intensity of the rotating field decreases the power consumption and consequent temperature rise as explained in (1) above; and
(3) The cost of the rotating field generating circuit can be cut down. The generating circuit for an intensive rotating field presents technical difficulties. Therefore, a smaller intensity rotating field simplifies the circuit and lowers the cost thereof.
As explained above, it is extremely significant to make the intensity of the rotating field small because this will achieve the three major advantages. Since the future trend to a high memory density in the magnetic bubble memory chip will require a highly intensive rotating field and high speed operation will require increase in frequency of the rotating field, minimization of the intensity of the rotating field will become all the more important.